Of planets and planetary nebulas.More than 2 centuries ago, English astronomer William Herschel spied several round, wispy objects that looked like the planet Uranus, which he had discovered just a few years earlier. He named the new objects planetary nebulas. Later observations revealed that the nebulas weren't planets, but clouds of gas blown off by dying stars. The misleading moniker (1) A name, title or alias. See alias. (2) A COM object that is used to create instances of other objects. Monikers save programmers time when coding various types of COM-based functions such as linking one document to another (OLE). See COM and OLE. stuck nonetheless. Two astronomers now suggest that planetary nebulas may have an intimate connection with planets after all. Raghvendra Sahai and John L. Trauger of NASA's Jet Propulsion Laboratory “JPL” redirects here. For other uses, see JPL (disambiguation). Jet Propulsion Laboratory (JPL) is a NASA research center located in the cities of Pasadena and La Cañada Flintridge, near Los Angeles, California, USA. in Pasadena, Calif., used the Hubble Space Telescope Hubble Space Telescope (HST), the first large optical orbiting observatory. Built from 1978 to 1990 at a cost of $1.5 billion, the HST (named for astronomer E. P. Hubble) was expected to provide the clearest view yet obtained of the universe. to examine several compact, relatively bright, and presumably pre·sum·a·ble adj. That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster. young planetary nebulas. The researchers sought out youthful nebulas in hopes that these clouds would retain clues to their formation. The images, which show that the nebulas have fingerlike projections, filaments, loops, arcs, and other complex shapes, highlight a long-standing puzzle. According to a popular model, planetary nebulas take their final form when the gaseous wind from a dying star plows into the shroudlike gas cloud that the star had previously ejected. The cloud is spherical, however, and the wind can't easily sculpt sculpt v. sculpt·ed, sculpt·ing, sculpts v.tr. 1. To sculpture (an object). 2. To shape, mold, or fashion especially with artistry or precision: it into the irregular shapes seen by Hubble. Tinkering with this scenario, theorists have added a high-speed jet of material that smashes into the cloud before the wind does. If the jet varies in direction and intensity, it would clear a zigzag path through the cloud. The wind following behind it would then expand faster in some directions than others, generating the complex shapes seen in nebulas. No one knows the exact origin of such a jet, but some astronomers suggest that the gravitational grav·i·ta·tion n. 1. Physics a. The natural phenomenon of attraction between physical objects with mass or energy. b. The act or process of moving under the influence of this attraction. 2. tug of a companion star causes the jet's variability. Sahai and Trauger take this concept a step further. They speculate that massive planets and failed stars known as brown dwarfs lie close to the dying star. The gravitational influence of these objects is a more likely source of variation in the jet, they suggest. Sahai and Trauger are not alone in their musings. In the Sept. 10, 1996 Astrophysical Journal, Noam Soker of the University of Haifa About 16,500 undergraduate and graduate students study in the university a wide variety of topics, specializing in social sciences, humanities, law and education. The University is broadly divided into six Faculties: Humanities, Social Sciences, Law, Science and Science Education, Social in Oranim, Israel, proposes that the destruction of massive planets and brown dwarfs spiraling into the dying star may generate the jet, as well as the wiggles within it. |
|
||||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion